rt_mutex

  

do_fork  -->  copy_process --> rt_mutex_init_task(p);    

关于rt_mutex，请参考Documentation/rt_mutex.txt

注解：

PI 是Priority Inheritance.

RT-mutexes with priority inheritance are used to support PI-futexes, 
which enable pthread_mutex_t priority inheritance attributes
(PTHREAD_PRIO_INHERIT). [See Documentation/pi-futex.txt for more details
about PI-futexes.]

在pi-futex.txt中：

futex（快速用户区互斥的简称）是一个在Linux上实现锁定和构建高级抽象锁如信号量和POSIX互斥的基本工具。

参考文章：http://zh.wikipedia.org/zh-cn/Futex